The present invention relates to bis (tri-tert-alkylphenoxy) diphosphaspiroundecanes, and to bis (2,4,6-tri-t-alkylphenoxy) diphosphaspiroundecanes in particular, as well as to polymer compositions which include tri-t-alkylphenoxy diphosphaspiroundecanes in stabilizing amounts.
A variety of alkylphenoxy diphosphaspiroundecanes are known in the art. Japanese Early Disclosure 1986-225, 191 of Oct. 9, 1986 by Tajima et al. discloses a number of bis (alkylphenoxy) diphosphaspiroundecanes, such as, bis(2-tert-butyl-4,6-dimethylphenoxy) diphosphaspiroundecane and bis(2,4-di-t-octylphenoxy) diphosphaspiroundecane. Bis (alkylphenoxy) diphosphaspiroundecanes are also disclosed by Japanese Patent No. 49-128044; U.S. Pat. Nos. 4,066,611 to Axelrod; 4,094,855 and 4,207,229 to Spivack; 4,305,866 to York et al.; 4,520,149 to Golder; 4,585,818 to Jung et al.; U.K. Patent Application GB No. 2 156 358 A and Japanese Patent Application 52 [1977]110829, Sept. 14, 1977, to Risner et al. Other diphosphaspiroundecane compounds known in the art include bis (2,6-di-t-butyl-4-methylphenoxy) diphosphaspiroundecane and bis (2,6-di-t-butyl-4-ethylphenoxy) diphosphaspiroundecane.
Virtually all commercial polymers contain one or more stabilizing compounds to protect the polymer against degradation of polymer properties by chain scission or undesired crosslinking during processing and product use. This degradation is particularly problematical with thermoplastic polymers, which typically are subjected to extreme processing temperatures. Not only does such degradation effect the physical properties of the composition, but may also cause the polymer to become discolored, thereby making the polymer aesthetically unappealing and causing the product to be rejected.
However, polymer stabilizers may be exposed to various adverse conditions during the course of their production, shipment, storage and use. One such condition which may adversely affect stabilizers is excessive to moisture either in the form of humidity or wetness. Although many stabilizers are used in the form of powders or granules, absorption of moisture may cause a stabilizer to clump or "block" thereby making the stabilizer difficult to handle during feeding and mixing operations. A consequence of such moisture exposure may be hydrolysis, which frequently reduces stabilizing properties and leaves the resin vulnerable to degradation.
Many phosphites, including some of the above-mentioned diphosphaspiroundecanes, may provide excellent stabilization when properly stored, either neat or after being compounded into the polymer. A few phosphites, such as tris(2,4-di-t-butylphenol)phosphite (TBPP), may exhibit good storage stability in humid environments, but do not provide the stabilizing efficacy of many members of the diphosphaspiroundecane class of stabilizer.
Although many of the above diphosphaspiroundecanes are capable of acting as polymer stabilizers, an improvement in the overall balance of properties would be realized if moisture resistance could be improved while maintaining excellent stabilizing properties. Indeed, a stabilizer which imparts good physical and color stability to a polymer while exhibiting improved resistance to moisture and hydrolysis offers significant practical advantages over many stabilizers known in the art.